This invention relates to turbocharger apparatus and, more especially, this invention relates to variable turbocharger apparatus.
Variable turbocharger apparatus is known comprising a housing, a compressor mounted for rotation in the housing, a turbine mounted for rotation in the housing, a first inlet for enabling air to be conducted to the compressor, an outlet for enabling air from the compressor to be conducted to an engine, a second inlet for enabling exhaust gases from the engine to be conducted to the turbine in order to rotate the turbine, a chamber which extends around the turbine and which receives the exhaust gases from the second inlet before the exhaust gases are conducted to the turbine, a bearing assembly for permitting the rotation of the turbine, a heat shield for shielding the bearing assembly from the exhaust gases, and a control system to control the speed of the turbine. One of the problems with such known variable turbocharger apparatus is the overall range limit, whereby if all of the gases are passed through the turbine, and if the variable turbocharger apparatus is designed to operate over a large flow volume, there is a point where the low down efficiency of the variable turbocharger apparatus starts to depreciate.